The invention relates to a transfer device in a transfer press or similar metal-forming machine.
Reference is made to the below listed U.S. patent applications:
(i) U.S. Application Ser. No. 380,508, filed July 17, 1989, based on German Application No. P 39 05 068.8 filed in Germany on Feb. 18, 1989-33986-; and
(ii) U.S. Application Ser. No. 428,587, filed Oct. 30, 1989, based on German Application No. P 39 05 069.6 filed in Germany on Feb. 18, 1989-33987-.
Transfer presses, bulky-part transfer presses, press installations are metal-forming machines, in which sheet metal parts are deformed by process steps, such as drawing and punching. For this purpose, the presses have at least one slide, at which a tool or a tool set (upper tool) is fastened which cooperates with a tool or tool set (lower tool) in the press bed or on a sliding table. The slides can be moved up and down by driving devices of the press. Intermediate depositing devices are mounted in areas between the frames leading to presses arranged behind them, these areas being known as idle stages. The changing of the tools or tool sets takes place by sliding tables which, for this purpose, can be moved into and out of the press.
In U.S. Pat. No. 4,625,540, a press is disclosed which has a device for the transferring of the sheet metal parts between working stages. This transfer device has two moving rails on both sides of the slides and tools and extending in conveying direction of the sheet metal parts. The moving rails are supported on the press bed by means of supports. In addition, a plate having rollers for placement on the moving rails is provided for each moving rail. Both plates are connected with one another by a strut. Two transfer rods are disposed at the strut which extend in parallel with respect to the moving rails. The transfer rods are connected with a cam follower lever which receives a swing motion from a control cam. On the side of the drive, the control cam is operatively connected with the main drive of the press. The transfer rods are rigidly connected with one another by traverses.
In guides of the transfer rods, cross bars are arranged which by an additional drive can be moved relative to the transfer rods. Vacuum suction devices are mounted at the cross bars which, by the movement of the cross bars, can be adjusted to the length of the sheet-metal parts. For the deforming stage, the cross bars with the vacuum suction devices can be adjusted into areas outside the slides and the tools. The transfer rods can be lifted and lowered by lifting devices which are not shown or explained in detail.
Accordingly, it is an object of the present invention to provide a transfer device which does not hinder the changing operation of the tools by means of supporting and driving devices affecting the transfer device below the level of the sheet metal conveyance.
The moving parts of the transfer device according to preferred embodiments of the present invention are advantageously low in mass and permit high accelerations during a shortened transfer movement and the return of the holding devices gripping the sheet metal parts. For this purpose, the transfer device carries out lifting and lowering movements for removing the sheet metal parts from the tools and for placing them in the tools.
As noted above, the low-mass construction of preferred embodiments of the present invention is advantageous. The driving devices and the devices of the transfer device which transfer and deflect the movements are assigned to the area (head area) of the press or presses, in which the driving devices for the slide or the slides are also housed. The transfer device can be retrofitted in press trains as well as in compact presses. Other advantages of preferred embodiments of the present invention are the short transfer movements of the carriages and their interim waiting position outside the working stages during the deforming phases.
In a particularly advantageous manner, the transfer device according to preferred embodiments of the present invention can be used in a new type of hybrid press installations with intermediate depositing devices set up between two working stages (idle stages) because the carriages, in pairs, can carry out different movements if the drive is designed correspondingly.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.